Species Diversity 20: 67–71 25 May 2015 DOI: 10.12782/sd.20.1.067 Description of a New Species of Branchiobdellida (Annelida: Clitellata) and Comparison with Other Cirrodrilus Species in Northern Honshu, Japan Akifumi Ohtaka1,3 and Stuart R. Gelder2 1 Department of Natural Science, Faculty of Education, Hirosaki University, Hirosaki 036-8560, Japan E-mail: [email protected] 2 Department of Math-Science, University of Maine at Presque Isle, 181 Main Street, Presque Isle, Maine 04769-2888, U.S.A. 3 Corresponding author (Received 10 October 2014; Accepted 17 February 2015) A new species of ectosymbiotic branchiobdellidan, Cirrodrilus iwakiensis sp. nov., is described from Cambaroides ja- ponicus (de Haan, 1849), the endemic freshwater Japanese crayfish, collected in Aomori Prefecture, northern Honshu Is- land, Japan. The anatomical features used to identify C. iwakiensis are compared with those of its closest congener, C. nip- ponicus (Yamaguchi, 1932), as well as C. aomorensis (Yamaguchi, 1934) and C. tsugarensis Gelder and Ohtaka, 2000 distrib- uted in the same region. Key Words: Annelida, Clitellata, branchiobdellidan, taxonomy, ectosymbiont, crayfish, Japan. dellidan. Cirrodrilus tsugarensis was described soon after the Introduction survey had finished, but specimens of the second species appeared to lack reproductive organs in segments 5 and 6. In East Asia, Branchiobdellida (Annelida: Clitellata) have Without details of the male anatomy, their generic affiliation been reported as ectosymbionts on freshwater crayfish and remained indeterminate and the species description could shrimp in China, southeastern Russia, the Korean Penin- not be completed. After 17 years of additional collecting, sula, and Japan (Ohtaka et al. 2012). Although Cirrodrilus specimens with recognizable genital organs were finally ob- is found across northern East Asia, there is no evidence to tained. This has resulted in the completion of the new spe- suggest any endemic species has been translocated between cies description presented here and also permitted an ana- the Asian mainland and Japan. Japan’s only indigenous cray- tomical comparison with other Japanese species. fish, Cambaroides japonicus (de Haan, 1849), is distributed across Hokkaido and northern Honshu Islands and has been reported to carry 11 species of Cirrodrilus (Yamaguchi 1934; Materials and Methods Gelder and Ohtaka 2000, 2002; Ohtaka 2010). Additional species reported from museum collections of Cambaroides Live Cambaroides japonicus were collected from 1997 japonicus include Cirrodrilus japonicus (Pierantoni, 1912) to 2014 at 21 sites on 30 occasions in Aomori Prefecture (q.v.), which Yamaguchi (1935) could not authenticate and (Table 1) and taken to Hirosaki University for examina- doubted the species validity, and Branchiobdella digitata tion. Branchiobdellidans were removed from their hosts and Pierantoni, 1906 (q.v.), which Timm (1991) regarded as in- preserved in 10% formalin or 70% ethanol solutions. Speci- certae sedis. Each island has its own Cirrodrilus species, with mens were dehydrated in a graded series of ethanol and nine in Hokkaido and Cirrodrilus aomorensis (Yamaguchi, water solutions, and either prepared for mounting whole 1934) and C. tsugarensis Gelder and Ohtaka, 2000 in north- (cleared in methyl salicylate, infiltrated with Canada balsam, ern Honshu. Only one translocation is known to have oc- and slide-mounted) or for wax sectioning (8 µm thick, hae- curred between these islands, when Japanese crayfish were matoxylin-eosin-stained and slide-mounted), then exam- introduced from Hokkaido to Akita Prefecture, northern ined on a compound microscope using bright-field and dif- Honshu. These hosts carried C. inukaii (Yamaguchi, 1934) ferential interference contrast (DIC) illumination. Mounted and C. uchidai (Yamaguchi, 1932) and soon both cray- specimens have been deposited in the Zoological Institute, fish and branchiobdellidans established viable populations Faculty of Science, Hokkaido University (ZIHU), Sapporo, which have remained restricted to the translocated area Japan; the National Museum of Natural History, Smith- (Gelder and Ohtaka 2000). sonian Institution (USNM), Suitland, MD, USA, and the During a distributional study of C. japonicus in Aomori New Brunswick Museum (NBM), Saint John, NB, Canada. Prefecture from 1997 to 1999, the senior author (AO) and Anatomical terminology used in this paper follows that de- his colleagues found two undescribed species of branchiob- scribed in Gelder and Williams (2015), where “ectal” means © 2015 The Japanese Society of Systematic Zoology 68 A. Ohtaka and S. R. Gelder nearer to the body surface, and “ental” farther from the sur- peristomial tentacles, alternating long (8) and short (7) with face. short one located at medial position, and with ventral lip medially incised and flanked by pair of small lateral lobes; Cirrodrilus iwakiensis sp. nov. 16 oral papillae present; jaws dissimilar, dorsal one larger [Japanese name: Iwaki-zarigani-mimizu] with semi-circular base narrowing to wing-like lateral tips, (Figs 1A–E, 2) large median tooth slightly curved anteriorly, and small teeth on anterior margin, ventral one with smaller, kidney- Material examined. Holotype: ZIHU 4930 removed shaped base, large median tooth and small teeth on anterior from Cambaroides japonicus collected by A. Ohtaka, 22 Sep- margin, with dental formula of 10/10 (5-1-4/5-1-4); single, tember 2012 from Oku-Shirasawa Stream on northwestern deep pharyngeal sulcus present; male organs small, glan- slope of Mt. Iwaki, Ajigasawa village, Aomori Prefecture, dular atrium club-shaped, length 0.3× segment diameter, Honshu Island, Japan (40°40′32″N, 140°15′29″E). Para- deferent lobes absent; muscular atrium tubular, length 0.2× types: ZIHU 4931, ZIHU 4932, USNM 1251839 collected segment diameter, penial sheath in ectal half, bursa small from same locality and host species as holotype by M. Mu- and spherical, penis eversible; spermatheca reduced, sper- kohyama on 16 October 1997; ZIHU 4934 from same host mathecal duct length 0.1× segment diameter, spermathecal species as holotype by A. Ohtaka, 9 September 1997 from bulb not recognized. Upper Uemata Stream, Imabetsu town. Additional non-type Etymology. Named after Mount Iwaki, on the slopes of specimens from same host species: ZIHU 4933 (Tokiwano, which the type locality is located. Mt. Iwaki, by A. Ohtaka, 18 June 2013), USNM 1251840, Description. Specimens 1.2–1.8 mm long, head with 1251841 (Yayoi, Mt. Iwaki, Hirosaki city, by A. Ohtaka, 11 shallow sulcus behind peristomium; body slim and pyri- May 2014), and NBM 010306–010308 (from type locality, form (Fig. 1A). Head width equal to or less than width of by A. Ohtaka and M. Mukohyama, 16 October 1997, 26 July segment 1, about equal to diameter of posterior attachment 1998, and 14 August 1998, respectively). disc. Dorsal segmental ridges, supernumerary muscles, and Diagnosis. Body slim and pyriform, 1.2–1.8 mm long dorsal or lateral appendages absent. Anterior nephridial fixed; head width equal to or less than width of segment 1; pores on segment 3 widely separated on its dorso-lateral dorsal segmental ridges, supernumerary muscles, and dorsal surface. Oral region cylindrical or funnel-shaped, surround- or lateral appendages absent; two anterior nephridial pores ed by 15 peristomial tentacles and narrow ventral lip, lat- widely separated on dorso-lateral surface; oral region cy- ter medially incised with pair of lobes flanking it (Fig. 1B). lindrical or funnel-shaped, surrounded by 15 dorso-lateral Tentacles consisting of seven short (one being median) and Fig. 1. Cirrodrilus iwakiensis sp. nov. A, Lateral view of paratype (ZIHU 4931); B, ventral view of peristomium of paratype (ZIHU 4932), median tentacle arrowed; C, jaws (dorsal over ventral), anterior view through mouth, paratype (ZIHU 4934); D, jaws (dorsal over ventral), lateral view (m = mouth) of holotype (ZIHU 4930); E, schematic lateral view of reproductive organs in segments 5 and 6 based on holotype (ZIHU 4930) and other material, showing only their ventral half (connecting duct in segment 5 was not observed), glandular atrium dotted; muscular atrium and spermathecal duct with tangential lines; bursa and spermathecal duct with longitudinal lines). Scale bars: A, 200 µm; B, 100 µm; C, D, 20 µm; E, 50 µm. New branchiobdellidan species in Japan 69 eight long ones, alternating around dorsal and lateral mar- across its anterior margin. Ventral jaw smaller, with oval or gins of oral region (Figs 1B, 2). Oral papillae 16 in number, kidney-shaped base and both large median tooth and small surrounding mouth. Jaws dissimilar in size and shape (Fig. teeth across its anterior margin. Dental formula 10/10 (5- 1C, D). Dorsal jaw larger, having semi-circular base and ta- 1-4/5-1-4). Single, deep sulcus extending around middle of pering lateral wing-like tips, bearing large, slightly anteriorly pharynx. curved median tooth and small, conical or rounded teeth Pair of testes located in segments 5 and 6 on anterior septal wall with stages from morulae to spermatozoa free within coelom in both segments. In each segment, two prominent sperm funnels each connect to a short, vas ef- ferens which then merge into a vas deferens (Fig. 1E); both vasa deferentia enter the glandular atrium ectally. Male or- gans difficult to see, being small and often pressed against ventral body wall. Glandular atrium club-shaped, its length 0.3× segment diameter, without deferent lobes or prostate gland (Fig. 1E). Muscular atrium